Linux servers & integration (infrastructure)

[lienux]

I have the need below to integrate & use (all free & open source for Linux):

1. Linux Enterprise Server
2. Fire Wall
3. Active directory
4. Enterprise Content Management
5. Payment Gateway

All the above need to be in one Sand Box . help me identifying the best distro for each of the above & how to integrate them in one single machine . also suggest me hardware required like CPU/Memory etc.

[Lazydog]

I have the need below to integrate & use (all free & open source for Linux):

1. Linux Enterprise Server

I would use RedHat as it is tried and true Servier Distro. Free would be Centos, SL.

2. Fire Wall

Iptables would work good here.

3. Active directory

Samba might be the choice here

4. Enterprise Content Management
5. Payment Gateway

Not sure what to pick here

All the above need to be in one Sand Box . help me identifying the best distro for each of the above & how to integrate them in one single machine . also suggest me hardware required like CPU/Memory etc.

As for memory and CPU get the best you can afford.